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  3. Mineral Resource Data System (MRDS)

Unnamed ('Sink Lake')

Occurrence in Alaska, United States with commodities Silver, Gold, Copper, Lead, Zinc
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10001623
MRDS ID A012387
Record type Site
Current site name Unnamed ('Sink Lake')

Geographic coordinates

Geographic coordinates: -131.40481, 55.10585 (WGS84)
Relative position This site represents four occurrences near an unnamed lake (informally called Sink Lake), about midway between the heads of Purple Lake and Crab Bay. The occurrences are are in section 16, T. 78 S., R. 93 E., of the Copper River Meridian, and are at elevations of about 200-400 feet around the lake, mainly near its southeast corner, and above the north shore. The coordinates are for the approximate center of the estimated half-mile-square area that contains the occurrences. The site corresponds to loc. 4 in Berg (1972 [I 684]), loc. 146 in Elliott and others (1978), and loc. 35a-d in Karl (1992). The location is accurate within about 0.1 mile.

Site location context

Political divisions (FIPS codes)

Prince of Wales-Hyder(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan A-5(quadrangle 1:63,360 scale)

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ketchikan(hydrologic unit)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Annette Island Indian Reservation(American Indian Reservation)

American Indian Reservation BIA(Type of land area)

BIA(Federal land areas administered by BIA)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Lead Primary
Zinc Critical Primary

Materials information

Materials Type of material
Barite Ore
Chalcocite Ore
Chalcopyrite Ore
Covellite Ore
Galena Ore
Magnetite Ore
Pyrargyrite Ore
Pyrite Ore
Sphalerite Ore
Stibnite Ore
Tetrahedrite Ore
Calcite Gangue
Hematite Gangue
Quartz Gangue

Alteration

  • (Local) Secondary copper and silver minerals suggest local supergene enrichment. Dolomitization of limestone; sericitization of rhyolitic volcanic rocks.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -131.40481, 55.10585
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this site include undivided, metamorphosed Silurian and Ordovician volcanic, sedimentary, and intrusive rocks; and a sequence of recrystallized, Upper Triassic carbonate, clastic, and rhyolitic rocks that unconformably overlies the Paleozoic rocks (Berg, 1972). The rocks are complexly folded and faulted, and were metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.? the principal occurrence consists of sulfide-bearing quartz-calcite ladder and stringer veins in a 300-foot by 500-foot area at or near a faulted contact between dolomitic limestone and locally sericitized rhyolite (Karl, 1992, loc. 35c). The veins aggregate as much as 10% of the total rock volume in this area. A 10-foot-wide shear zone at the contact contains quartz veins that predate the shearing (Karl, 1992, loc. 35). The veins, which are mostly in the dolomitic limestone, contain galena, sphalerite, pyrite, hematite, tetrahedrite, stibnite, malachite, and barite. Samples collected in the 1930s by the USGS reportedly also contained chalcopyrite, covellite, chalcocite, and a trace of pyrargyrite ('ruby silver') (Berg, 1972, loc. 4). ? Sheared rhyolite sampled in the 1970s by private interests reportedly contained massive chalcopyrite up to 2 inches thick, malachite coatings, and up to 50% magnetite (Karl, 1992). Karl's samples of sulfide- and/or magnetite-bearing quartz veins and country rocks at the sheared contact of greenstone and rhyolite contained up to 300 ppm Zn and 20 ppm Mo (Karl, 1992, loc. 35a, b). Other samples of sulfide-bearing quartz veins and of mineralized country rocks collected during USGS and private investigations in the 1930s, 1970s, and the early 1990s assayed as much as 0.03 oz. Au/ton, 20.4 oz. Ag/ ton, more than 2% Cu, 12.43 % Pb, more than 1% Zn, more than 1% Sb, 3000 ppm Ba, and 15 ppm Mo (Karl, 1992, loc. 35c).
  • Age = Late Triassic or younger.

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Sheared rhyolite sampled in the 1970s by private interests reportedly contained massive chalcopyrite up to 2 inches thick, malachite coatings, and up to 50% magnetite (Karl, 1992). Karl's samples of sulfide- and/or magnetite-bearing quartz veins and country rocks at the sheared contact of greenstone and rhyolite contained up to 300 ppm Zn and 20 ppm Mo (Karl, 1992, loc. 35a, b). Other samples of sulfide-bearing quartz veins and of mineralized country rocks collected during USGS and private investigations in the 1930s, 1970s, and the early 1990s assayed as much as 0.03 oz. Au/ton, 20.4 oz. Ag/ ton, more than 2% Cu, 12.43 % Pb, more than 1% Zn, more than 1% Sb, 3000 ppm Ba, and 15 ppm Mo (Karl, 1992, loc. 35c).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Karl, 1992

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins (Cox and Singer, 1986; model 22c)

Reporter information

Type Date Name Affiliation Comment
Reporter 06-JUL-1999 H.C. Berg U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.